Quality, bioactive compounds and antioxidant capacity of selected climacteric fruits with relation to their maturity

Scientia Horticulturae 221 (2017) 33–42

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Research paper

Quality, bioactive compounds and antioxidant capacity of selected climacteric fruits with relation to their maturity

MARK

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Sirithon Siriamornpun , Niwat Kaewseejan Research Unit of Process and Product Development of Functional Foods, Department of Food Technology and Nutrition, Faculty of Technology, Mahasarakham University, Maha Sarakham 44150, Thailand

A R T I C L E I N F O

A B S T R A C T

Keywords: β-Carotene Climacteric fruit Flavonoid Green fruit Ripe fruit Individual phenolic Ripening stage Tropical fruit

The variation in physicochemical characteristics, bioactive components and antioxidant capacity of three climacteric fruits, namely banana, mango and papaya were investigated. Correlations between ripeness and bioactive compounds as well as antioxidant capacity were also studied. From physicochemical analysis, hardness and firmness of fruit declined during ripening, which were consistent with loss in crude fiber and increase in total soluble solid. Total phenolic, vitamin C and antioxidant capacity were superior for green fruit, while opposite was observed for β-carotene content. Ripening clearly decreased total phenolic acids and total flavonoids contents determined using RP-HPLC. We found that ripening was correlated at a highly significant level with individual phenolic acids (gallic, vanillic, chlorogenic and sinapic acids) and individual flavonoid (quercetin) (p < 0.001), whereas a very significant correlation (p < 0.01) was observed with vitamin C, βcarotene and caffeic acid. However, no correlation existed between ripening and antioxidant capacity. Our findings have provided novel information about how best to select the appropriate maturity of fruits that contains the highest amount of specific bioactive markers linking to the best health benefits or functional properties.

1. Introduction Nowadays, the choice of fruit consumption is no longer based purely on taste and personal preference, but it is also based on a desire for better health. The consumption of various types of tropical fruits has been increasing in the international and domestic markets due to them possessing high nutritional and functional significance for human health. Tropical fruits play important roles both economically for commercialization and nutritionally for consumption (Cardoso et al., 2011). Epidemiological studies indicate that dietary intake of fruits prevents chronic diseases such as cancer, diabetes and other noncommunicable diseases (Hung et al., 2004). Thus, research on the health benefits of fruits has increased significantly in recent years, not only in terms of their being sources of basic nutrients but also bioactive components (Kubola and Siriamornpun, 2011; de Carvalho-Silva et al., 2014). Thailand is known as one of the most biodiversity-rich countries, and it has a large number of fruit species, especially tropical fruits. These fruits have been reported as good sources of many bioactive phytochemicals, which are considered to be responsible for health beneficial effects and for reducing the risk of many diseases caused by

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oxidative stress, such as cancer and cardiovascular diseases (Charoensiri et al., 2009; Rangkadilok et al., 2007; Siriamornpun et al., 2015). Recently, many authors have reported that there were a large number of Thai tropical fruits that contain a high content of bioactive compounds, particularly banana, mango and papaya (Charoensiri et al., 2009; Patthamakanokporn et al., 2008). These fruit qualities and the amount of their bioactive components are influenced by cultivar and ripening stage, amongst other factors (Ibarra-Garza et al., 2015; Schulz et al., 2015). Moreover, these fruits are a climacteric fruit, which can continue the ripening process even when harvested from the parent tree; hence the ripening stage is the most important factors for determining its sensory quality (Prasanna et al., 2007). Ripening process also involves directly on the various physiological, biochemical and molecular changes include degradation or synthesis and accumulation of bioactive components, such as phenolic compounds, vitamin C and carotenoids (Tiwari and Cummins, 2013; IbarraGarza et al., 2015). Thai people commonly use fresh green fruit pulp in cuisine, such as spicy salad (chopped green fruit with chili sauce and other spices), or consume green fruit with chili and salt powder for dipping, whereas ripe fruit are eaten in fresh, juice and dessert. The fruits are consumed in fresh or in a processed form under appropriate

Corresponding author. E-mail address: [email protected] (S. Siriamornpun).

http://dx.doi.org/10.1016/j.scienta.2017.04.020 Received 27 November 2016; Received in revised form 3 February 2017; Accepted 14 April 2017 0304-4238/ © 2017 Elsevier B.V. All rights reserved.

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Turoni S.r.l., Italy) and results were expressed as the maximum force (in Newtons) that were needed to puncture the fruits.

ripened stage (green and ripe fruits) based on the requests of consumers, but nutritional value and health benefits as well as bioactive markers have significant differences between green and ripe fruits. For example, Ding et al. (2001) demonstrated that the content of chlorogenic acid in loquat fruit increased during ripening stage. Similarly, Schulz et al. (2015) reported that green fruit of juçara contained the highest flavonoid quercetin content. On the other hand, our previous study showed that some phenolic acids and biological activities were superior for green jujube fruit compared to the ripe fruit (Siriamornpun et al., 2015). However, if the purpose is to use the fruit as a functional food for improving health beneficial effects or as an ingredient for the food industry, the knowledge of changes in bioactive compounds and antioxidant activity between the green and ripe stages is essential to select the most suitable ripening stage. Therefore, it was of our interest to investigate the variations in physicochemical characteristic, bioactive component and antioxidant capacity of the green and ripe fruits of three commonly consumed and popular fruits, namely banana, mango and papaya, which have not been well studied. The correlations between the bioactive compounds (vitamin C, β-carotene, individual phenolic acids and individual flavonoids) and antioxidant activity in these fruits with ripening stage were also studied for the best of our knowledge.

2.4. Extraction of fruit samples The samples were extracted using the method described previously by Bakar et al. (2009). The dried powdered fruits (1 g) were extracted three times with 10 ml of 80% methanol for 2 h at room temperature on an orbital shaker set at 180 rpm. The mixture was centrifuged at 1400 × g for 20 min and the supernatant was transferred into a 30 ml vial. The supernatant was then used to determine the antioxidant activity and total phenolic content as well as HPLC analysis for phenolic acids and flavonoids. 2.5. Determination of total phenolic content (TPC)

2. Materials and methods

The TPC was determined using the Folin-Ciocalteau method following Bakar et al. (2009). Briefly, 0.3 ml of extract solution was mixed with 2.25 ml of diluted (1:10 with water) Folin-Ciocalteau reagent. After 5 min, 2.25 ml of 6% (w/v) sodium carbonate was added and then left to stand for 90 min at room temperature. After that, the absorbance of the mixture was measured at 725 nm using a spectrophotometer. Results were expressed as mg gallic acid equivalents (GAE) per g dry weight (mg GAE/g DW).

2.1. Chemicals and reagents

2.6. Extraction and determination of vitamin C

Phenolic acid standards, such as gallic, ferulic, p-hydroxybenzoic, protocatechuic, p-coumaric, caffeic, syringic, sinapic, chlorogenic and vanillic acids, and flavonoid standards, such as rutin, myricetin, luteolin, quercetin, apigein and kaempferol, were purchased from Sigma–Aldrich Co. (St. Louis, MO, USA). Standards of beta-carotene and ascorbic acid were obtained from Sigma Chemical Co. (St. Louis, MO, USA). The 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,4,6-tripiridyls-triazine (TPTZ), Folin–Ciocalteu’s reagent, methanol and acetonitrile used in the HPLC analysis were purchased from Merck (Darmstadt, Germany). All other solvents were purchased from Fisher Scientific (Leicester, UK) and were of analytical grade.

Vitamin C in the samples was extracted and quantified according to the method described by Abushita et al. (1997). For extraction, each dried sample (10 g) was mixed with 50 ml of 2% metaphosphoric acid while being shaken at room temperature for 2 h. After that the mixture was filtered through filter paper and the filtrate was then kept at −20 °C until analysis. The content of vitamin C in the sample was determined using HPLC (LC–20AC, Shimadzu, Japan), SPD–M20A diode array detection and chromatographic separations on a LUNA C–18 column (4.6 × 250 mm, 5 μm). The mobile phase used was 0.1 M KH2PO4/methanol (97:3) at a flow rate of 1.0 ml/min. The isocratic elution was performed as described previously (Abushita et al., 1997). Operating conditions were as follows: column temperature 40 °C, injection volume 20 μl and UV–diode array detection at 225 nm.

2.2. Fruit materials and sample preparation

2.7. Extraction and determination of β-carotene

Various cultivars of three fruits (banana (Musa sapientum L.), mango (Mangifera indica L.) and papaya (Carica papaya L.), which are commonly cultivated and consumed in Thailand, were studied. The details of characteristics and biological activities of selected fruits investigated are shown in Table 1. We also provide the information about Thai style cooking of green and ripe fruits for an alternative way of cooking which may be useful for general consumers. About 2–3 kg of each fruit were collected from the local markets in Maha Sarakham Province, Northeastern Thailand. Each fruit was classified into two groups based on the color of its skin corresponds to commercial maturity, namely, unripe (green) and ripe (yellow) fruits. To obtain the ripe fruit, green fruits were sampled and allowed to ripen in paper boxes at ambient temperature for 24–48 h. Both green and ripe fruits were cleaned and separated into pulp, peel and seed. The edible part (green and ripe pulps) was cut into small pieces, freeze dried and stored in sealed plastic bags at −20 °C until analysis.

The β-carotene content in the samples was extracted and quantified using a method described previously (Nhung et al., 2010; Kubola et al., 2013). A sample (2 g) was extracted three times with 50 ml of acetone while being shaken for 25 min at room temperature and filtered through filter paper. The filtrate was then transferred to a separating funnel containing 15 ml of petroleum ether followed by the addition of distilled water. The lower phase was discarded, and the upper phase was washed five times with distilled water to completely remove the acetone. The resulting sample solution in petroleum ether was transferred to a volumetric flask and made up to a total volume of 50 ml with petroleum ether. The final sample solution was filtered through 0.45 μm membrane filters and 20 μl were injected for HPLC analysis. HPLC analysis was performed using Shimadzu LC-20AC pumps, SPDM20A diode array detection and chromatographic separations on a C18 column (4.6 mm × 250 mm, 5 μm). The mobile phase used was acetonitrile/dichlorometane/methanol (70:20:10) at a flow rate of 1.3 ml/min. The isocratic conditions used for elution were described previously (Kubola et al., 2013). Operating conditions were as follows: column temperature 40 °C, injection volume 20 μl and UV–diode array detection at 472 nm. The β-carotene in the samples was identified by comparing retention times of standard β-carotene and the content was calculated using the linear equation obtained from a calibration curve of the external standard.

2.3. Determination of physicochemical characteristics The value of total crude fiber content was determined by the standard method of AOAC (AOAC, 1998). The total soluble solid (TSS) was measured using a digital refractometer (Atago Rx 5000, Atago Co. Ltd., Japan) and the results were expressed as °Brix. Texture analysis (hardness, firmness and crispness) was performed by measuring the maximum shear force using a texture analyzer (TR 53205, TR 34

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120–140/5–10

110–130/3–7

95–105/3–7

150–180/5–7

120–130/4–7

130–140/5–7

Mango Nam Dokmai

Khiew Sawoey

Kaew

Papaya Khak Dam

Hawaii

Holland

C

B

12–14 × 25–27 cm oval shape with obtuse apex 12–14 × 31–35 cm round shape with obtuse apex

12–14 × 35–40 cm round shape with acute apex

7–9 × 14–16 cm round shape with acute apex 6 × 9 cm oval shape with obtuse apex

7–9 × 15–18 cm round shape

2–3 × 8–10 cm oval shape 3–4 × 21–25 cm angular shape

Average size and shape of fruit

White/ orange White/ orange

White/ orange

White/ yellow White/ yellow White/ yellow

White/ light yellow White/ white

Pulp colour (green/ ripe)

Days after full bloom. Days after collecting green fruit. Data are retrieved from Medicinal Plants Information Center, Mahidol University.

70–80/3–5

Hom

A

50–55/2–5

Harvesting (green A/ripe B)

Banana Khai

Fruits

Table 1 The characteristics and biological activities of Thai banana, mango and papaya fruits.

Green/yellow

Green/ yelloworange Green/yellow

Light green/ yellow Dark green/ yellow Green/yellow

Green/light yellow

Green/yellow

Peel colour (green/ripe)

Sweet

Sweet

Sweet

Sweet, aromatic Sweet, aromatic Sweet, aromatic

Sweet, aromatic Sweet, aromatic

Flavour/taste (at ripening stage)

Green: hot and spicy salads with onion, salt and fish sauce, light curry with meat or pork Ripe: eat as fresh fruit, garnish

Green: eat as fresh fruit with chili paste or sweet fish sauce, hot and spicy salads, hot curry with pork, as a garnish Ripe: eat as fresh fruit, juice, dessert i.e. mango with coconut rice, as ingredient in fruit cake and ice-cream

Green: eat as fresh with chili paste, as ingredient in chili paste, boiling, garnish, hot and spicy salad, peeled and cooked as curry with meat Ripe: eat as fresh fruit, juice, dessert i.e. banana in coconut, ice cream, cake, topping

Thai style cooking

Apoptosis inhibition, DNA damage prevention, cytotoxic, carcinogenesis inhibition, nephrotoxic

Acetylcholinesterase inhibition, anti-hyperglycemic, anti-hypertensive, anti-hypothyroidism, antioxidant

Amylase inhibition, anti-hyperglycemic, antiinflammatory, anti-viral and anti-bacterial

Biological activityC

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0.41 ± 0.09b,B 0.39 ± 0.03c,B 0.52 ± 0.06a,B 0.44 9.37 ± 0.46b,A 12.87 ± 0.69 a,A 8.21 ± 0.41c,A 10.15

8.67 ± 0.46b,A 10.56 ± 0.69a,A 15.21 ± 0.41c,A 11.48

NA NA –

Green

Crispness

Ripe

DPPH% scavenging activity was measured according to the method described by Brand-Williams et al. (1995). Each extract solution (0.1 ml) was added to 3 ml of a freshly prepared 0.1 mM DPPH solution dissolved in methanol. The mixture was shaken and left to stand at room temperature for 30 min in the dark. The absorbance was read at 517 nm against a control using a spectrophotometer. Results were expressed as an IC50 value, which is the concentration of the extract that scavenges 50% of the DPPH%.

NA NA –

2.8. DPPH% scavenging activity assay

0.31 ± 0.19b,B 0.49 ± 0.04c,B 0.62 ± 0.07a,B 0.47

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0.36 ± 0.03b,B 0.30 ± 0.05c,B 0.38 ± 0.07a,B 0.35 8.53 ± 1.01a,A 8.17 ± 0.91a,A 7.30 ± 0.83a,A 8.00 9.73 ± 0.12c,A 14.77 ± 0.06a,A 11.37 ± 0.06b,A 11.96 8.67 ± 0.06b,B 8.73 ± 0.06ab,B 8.83 ± 0.06a,B 8.74 1.10 ± 0.25b 1.85 ± 0.08a 1.20 ± 0.15b 1.38 Papaya Khak Dam Hawaii Holland mean

0.96 ± 0.05c 1.61 ± 0.07a 1.13 ± 0.04b 1.23

0.31 ± 0.03b,B 0.33 ± 0.01c,B 0.36 ± 0.04a,B 0.33 8.53 ± 1.01a,A 8.17 ± 0.91a,A 7.30 ± 0.83a,A 8.00 17.56 ± 0.22a,A 10.47 ± 0.16c,A 15.03 ± 0.36b,A 14.35 3.21 ± 0.36b,B 5.65 ± 1.06a,B 3.11 ± 0.26c,B 3.99 1.52 ± 0.01b,A 1.72 ± 0.04a,A 1.64 ± 0.08a,A 1.63 Mango Nam Dokmai Khiew Sawoey Kaew mean

1.35 ± 0.06c,B 1.40 ± 0.12b,B 1.57 ± 0.02a,B 1.44

34.29 ± 3.61b,A 65.83 ± 3.75a,A 50.06 24.23 ± 0.07b,A 26.63 ± 0.23a,A 25.43 5.30 ± 0.07b,B 6.60 ± 0.14a,B 5.95 1.90 ± 0.06a,B 1.71 ± 0.26b,B 1.81 2.02 ± 0.21a,A 2.13 ± 0.08a,A 2.08 Banana Khai Hom mean

Green Ripe Green

The fruit qualities (crude fiber, total soluble solid and texture) in green and ripe fruits of banana, mango and papaya are shown in Table 2. The results showed significant differences among cultivars and maturity of three fruits studied related to fruit qualities. The crude fiber decreased continuously during ripening, although some changes were not statistically significant. The content of crude fiber (%) ranged from 0.96 in the ripe fruit of Khak Dam papaya to 2.1 in the green fruit of Hom banana. Yahia et al. (2011) reported that the fiber content ranged from 0.5–22.8, 1.2–1.8 and 1.4–1.8% for banana, mango and papaya, respectively. The crude fiber content of the green fruit of banana and mangos was slightly higher than that of the ripe fruit. In contrast, the crude fiber content of papaya was not significantly different between

Ripe

3.1. Physicochemical characteristics

Green

3. Results and discussion

Total soluble solid (% °Brix)

Analysis of variance (ANOVA) was conducted to determine any significant differences in measurements using the SPSS statistical software (SPSS 16 for Windows; SPSS Corporation, Chicago, IL). The confidence limits used in this study were based on 95% probability (p < 0.05). Partial correlation coefficient was performed to compare the correlations between various parameters with the ripening stage, whereas the correlation between bioactive compounds and antioxidant activity was described as Pearson correlation analysis.

Crude fiber (%)

2.11. Statistical analysis

Fruits

Table 2 Physicochemical characteristics of green and ripe fruits of three tropical fruits cultivated in Thailand.

Hardness

Ripe

HPLC analysis of phenolic acids and flavonoids were performed using Shimadzu LC-20AC pumps, SPD–M20A diode array detection and chromatographic separations on a column Inetsil ODS-3, C18 (4.6 mm × 250 mm, 5 μm). The mobile phase consisted of acetic acid pH 2.74 (solvent A) and acetonitrile (solvent B) at a flow rate of 0.8 ml/ min. The gradient elution conditions were described previously by Kubola and Siriamornpun (2011). The operating conditions were as follows: column temperature 38 °C, injection volume 20 μl and UVdiode array detection at 280 nm for phenolic acids and 370 nm for flavonoids. Phenolic compounds in the samples were identified by comparing their relative retention times and UV spectra with those of authentic compounds and were detected using external standard methods.

7.32 ± 0.73a,B 6.38 ± 1.19b,B 6.85

2.10. Determination of individual phenolic acids and flavonoids

Results are expressed as mean ± SD (n = 3). Values with different letters in the same column (a–c) and in the same row (A–B) represent significant differences at p < 0.05. NA, not applicable.

0.13 ± 0.02a,B 0.10 ± 0.02a,B 0.15 ± 0.01a,B 0.13 1.99 ± 0.15a,A 2.03 ± 0.54a,A 1.35 ± 0.13a,A 1.79

0.13 ± 0.03a,B 0.10 ± 0.04a,B 0.14 ± 0.01a,B 0.12 2.86 ± 0.15a,A 2.03 ± 0.54a,A 2.45 ± 0.13a,A 2.46

0.32 ± 0.07a,B 0.29 ± 0.05b,B 0.31 1.38 ± 0.72b,A 4.09 ± 0.41a,A 2.74

Green

Firmness

Texture (N)

The FRAP assay was conducted as described by Benzie and Strain (1996). The fresh FRAP reagent was made by adding 100 ml of 0.3 M acetate buffer pH 3.6, 10 ml of 10 mM TPTZ solution in 40 mM HCl and 10 ml of 20 mM FeCl3 in a ratio of 10:1:1 and 12 ml of distilled water at 37 °C. In brief, 60 μl of the extract, 180 μl of distilled water and 1.8 ml of FRAP reagent were added to the same test tube and thoroughly mixed. After incubation at 37 °C for 4 min, the absorbance was measured at 593 nm against a control. Results were expressed as mmol Fe(II) per g dry weight (mmol Fe(II)/g DW).

Ripe

2.9. Ferric reducing antioxidant power (FRAP) assay

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3.2. Quantification of total phenolic, vitamin C and β-carotene

the ripe and green fruit. The overall mean of the crude fiber content evaluated in three types of fruit was significantly higher in banana, followed by mango and papaya, respectively. Changes in crude fiber during fruit ripening could be due to structural changes, polysaccharide degradation and enzymatic activity (Tharanathan et al., 2006). The increases in total soluble solid (TSS) were observed in all fruits studied with ripening stage (Table 2). Similar changes have been reported in many cultivars of strawberry and mango during ripening (Ornelas-Paz de et al., 2013; Ibarra-Garza et al., 2015). The increase in TSS during ripening has been attributed to the hydrolysis of starch to glucose and fructose by the action of amylases, which are used as substrates for fruit respiration (Eskin et al., 2013). Among all fruits tested, the ripe fruit of Hom banana showed the highest TSS value (26.6% °Brix) and the green fruit of Kaew mango showed the lowest TSS value (3.1% °Brix). The TSS of each fruit was arranged in the following order: banana > mango > papaya. According to a previous study, the fruits with the highest possibility of consumer acceptance are those with high levels of TSS (De Souza et al., 2012). Texture parameter evaluation (hardness, firmness and crispness) in green and ripe fruits of banana, mango and papaya was conducted as this is an important attribute for the sensory properties, and the results are also presented in Table 2. The hardness, firmness and crispness of all fruits tested changed during the ripening and significant differences were verified between the cultivars of the fruits. The means of all parameters were significantly higher in green fruit than those of ripe fruit in all samples studied. The various texture properties of fruit can change rapidly during fruit ripening or in fresh-cut fruit as well as due to harvesting conditions (Toivonen and Brummell, 2008). They also demonstrated a firmness loss of 12% between green and ripe fruits; but, the harvesting conditions were not specified in their study. However, from our experience the harvesting stage is highly dependent on the variety involved, as reflected by consumer preference. Additionally, the results of this present study demonstrated that the declines in hardness, firmness and crispness were consistent with losses in the crude fiber during fruit ripening, while the TSS showed a reversed trend. The changes in firmness and hardness were also highly correlated at p < 0.01 with those of the crude fiber (r = 0.681 and 0.453, respectively) and the TSS (r = −0.684 and −0.566, respectively), which can be used as ripening indicators for banana, mango and papaya.

Variations in total phenolic, vitamin C and β-carotene contents of green and ripe fruits of banana, mango and papaya are shown in Table 3. We found significant differences in the contents of bioactive compounds between the ripening stage, cultivar and type of fruit. These differences could be due to a combination of genetic factors and growth environment factors as well as ripening stages, thus influencing the biosynthesis of bioactive compounds in fruits (Akbari et al., 2012). Phenolic compounds are considered to be an important bioactive compound found in plants due to their various potential biological activities, such as antioxidant, anticancer and anti-inflammatory actions (Shahidi and Naczk, 2004). The statistical analysis revealed that the TPC in all fruits studied decreased significantly (p < 0.05) during ripening, although some changes were not statistically significant (Table 3). Similar changes have been reported by many researchers who have found that the concentration of phenolics in various fruits decreases as ripening (Gruz et al., 2011; Ornelas-Paz de et al., 2013; Ibarra-Garza et al., 2015). Gayosso-Garcia et al. (2010) also reported that the green stage of Maradol papaya showed the higher phenolic content and antioxidant activity when compared to the ripe stage, in line with our findings. Accordingly, the present results suggest that ripening reduces TPC in fruits. In our study, the TPC of fruits ranged from 0.12 mg GAE/g DW in banana (Khai and Hom) to 5.58 mg GAE/g DW in mango (Kaew), with the descending order of mango > papaya > banana. Vasco et al. (2008) classified fruits into three groups according to their phenolic content: low (< 1 mg GAE/g), medium (1–5 mg GAE/g) and high (> 5 mg GAE/g). This classification indicates that banana and papaya have a low amount of phenolics, whereas mangos exhibit a medium amount. This suggests that mango is a good source of phenolic compounds in comparison with banana and papaya. Vitamin C is important for human health because it is an antioxidant compound of natural origin in foods (Almeida et al., 2011). A similar trend to TPC result was observed in the vitamin C content; a decrease in vitamin C was found between the ripening stages (Table 3), indicating that green fruit has the highest vitamin C content. Our findings agreed with previous research reporting a decrease in vitamin C content during fruit ripening for guava fruit, carob (Ceratonia siliqua L.) and peaches (Bashir and Abu-Goukh, 2003; Benchikh et al., 2014; Liu et al., 2015). The decrease in vitamin C has been attributed to its oxidative degradation in various fruits at different ripening stages. As shown in Table 3, the green fruit of Hom banana (0.49 mg/g DW) showed the highest content of vitamin C when compared to other samples studied.

Table 3 Total phenolic, vitamin C and β-carotene contents in green and ripe pulp extracts of three fruits studied. Fruits

TPC (mg GAE/g DW)

β-carotene (mg/g DW)

Vitamin C (mg/g DW)

Green

Ripe

Green

Ripe

Green

Ripe

Banana Khai Hom mean

0.34 ± 0.42a,A 0.19 ± 0.20b,A 0.27

0.12 ± 0.19a,B 0.12 ± 0.17a,B 0.12

0.27 ± 0.02b 0.49 ± 0.02a,A 0.38

0.28 ± 0.02b 0.38 ± 0.01a,B 0.33

7.03 ± 0.80a,B 7.41 ± 2.47a,B 7.22

51.09 ± 3.35a,A 35.98 ± 6.42b,A 43.54

Mango Nam Dokmai Khiew Sawoey Kaew mean

3.27 ± 0.73a,A 2.74 ± 0.26c,A 3.05 ± 0.23b,B 3.02

1.11 ± 0.14b,B 1.15 ± 0.02b,B 5.58 ± 1.13a,A 2.61

0.36 ± 0.02a,A 0.35 ± 0.03a,A 0.36 ± 0.02a,A 0.36

0.28 ± 0.02a,B 0.27 ± 0.01a,B 0.28 ± 0.01a,B 0.28

3.45 ± 0.12a,B 2.18 ± 0.10b,B 3.01 ± 0.42a,B 2.88

50.89 ± 1.19a,A 20.54 ± 0.89c,A 45.47 ± 0.68b,A 39.00

Papaya Khak Dam Hawaii Holland mean

0.36 ± 1.14a 0.37 ± 0.98a 0.32 ± 0.42b 0.35

0.41 ± 1.19ab 0.42 ± 0.89a 0.40 ± 0.68b 0.41

0.08 ± 0.01b 0.15 ± 0.01b,A 0.34 ± 0.03a,A 0.19

0.14 ± 0.03a 0.13 ± 0.04b,B 0.14 ± 0.08a,B 0.14

ND ND ND –

6.73 ± 1.19b 9.50 ± 0.89a 1.90 ± 0.68c 6.04

Results are expressed as mean ± SD (n = 3). Values with different letters in the same column (a–c) and in the same row (A–B) represent significant differences at p < 0.05. TPC, total phenolic content. ND, not detected.

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As shown in Table 4, the FRAP values of fruits ranged from 0.07 mmol Fe(II)/g DW in two cultivars of banana to 1.21 mmol Fe (II)/g DW in Kaew mango, with the descending order of mango > papaya > banana. In most cases, the FRAP value of the green fruit was higher than that of the ripe fruit, which may be due to the green fruit containing high amounts of vitamin C and phenolics. A similar tendency has been reported by Siriamornpun et al. (2015) who found the green jujube fruit showed stronger antioxidant capacity than the ripe fruit. For banana, the green fruit of Hom exhibited the highest FRAP value (0.20 mmol Fe(II)/g DW), whereas the green fruit of Khai had the lowest FRAP value. For mangos, the FRAP values ranged from 0.07 mmol Fe(II)/g DW in the ripe fruit of Nam Dokmai to 1.21 mmol Fe(II)/g DW in the green fruit of Kaew. In papaya, the FRAP values range from 0.13 mmol Fe(II)/g DW in the ripe fruit of Holland to 0.42 mmol Fe(II)/g DW in the green fruit of Holland. The observed differential FRAP activities of the three fruits could be due to the presence of different bioactive compounds in each cultivar or type of fruit. A previous study demonstrated that the high antioxidant capacity in the fruit from Brazil was attributed to its high content of phenolics and flavonoids (de Carvalho-Silva et al., 2014).

The vitamin C content of fruits ranged from 0.13 mg/g DW in Hawaii papaya to 0.49 mg/g DW, with the descending order of banana ≈ mango > papaya. Following the vitamin C classification in fruit proposed by Ramful et al. (2011) using low (< 0.3 mg/g), medium (0.3–0.5 mg/g) and high (> 0.5 mg/g), banana and mango had a medium level while papaya had a small amount of vitamin C (less than 0.3 mg/g). However, these values were higher than that of atemoya (0.029 mg/g), dragon-fruit (0.021 mg/g) and carambola fruit (0.027 mg/g) as reported by Valente et al. (2011). Wall (2006) reported the overall means of vitamin C content in banana and papaya cultivars grown in Hawaii were 0.01 and 0.51 mg/g, respectively. Fruits containing high contents of vitamin C were guava, kiwifruit, longan and strawberry (Isabelle et al., 2010). However, we think that the three fruits studied are good sources of vitamin C that could be used in the food, pharmaceutical and cosmetic industries. β-Carotene plays an important role in human health by preventing damage to cells and tissues from free radicals and is used as a natural colorants in food (Oreopoulou and Tzia, 2007). The increases in βcarotene content were observed in all fruits studied during ripening (Table 3), which showed reversed trends with TPC and vitamin C contents. Our result agreed with previous research reporting an increase of carotene content in ripening fruit from many mango cultivars (Ibarra-Garza et al., 2015; Ornelas-Paz de et al., 2013), concluding ripening enhances β-carotene content in these fruits. The β-carotene content in ripe fruit of Khai banana (51.09 mg/g DW) showed a higher level than the other samples tested. The order of the mean values of β-carotene content in the three fruits was mango > banana > papaya. The amounts of β-carotene found in our study are higher than those of orange, mandarin and grapefruit (from 0.02 to 0.11 mg/g DW) as reported by Rincón et al. (2005). Comparison of green and ripe fruits from three fruits showed that the ripe fruit had higher amounts of β-carotene than the green fruit. β-Carotene in the green fruit of all papaya cultivars was not found; however in the ripe fruits it was detected in the range of 1.90–9.50 mg/g DW. The differences in the amount of β-carotene could be due to differences in the ripening of the fruits because the carotenoid levels can change dramatically during ripening. They show an accumulation of β-carotene that is reflected in the change of color in the fruit during ripening (Vuong et al., 2002). Ajila et al. (2007) showed that the content of carotenoid in Indian mango was 4–8 folds higher in ripe mango fruits than green mango fruit. Additionally, a previous study has reported that the levels of carotenoids in some fruit increases during ripening (Aoki et al., 2002).

3.4. Composition and content of bioactive phenolic acids Phenolic compounds in fruits have received significant attention in recent years due to their potent antioxidant capacities and their ability to reduce the risk of diseases caused by oxidative stress, such as cancer (Kubola and Siriamornpun, 2011; Deng et al., 2013; de Carvalho-Silva et al., 2014; Siriamornpun et al., 2015). In present study, ten phenolic acids were identified and quantified in the green and ripe fruits from the fruits studied by RP-HPLC analysis (Table 5). From these, five were hydroxybenzoic acids (gallic, protocatechuic, p-hydroxybenzoic, vanillic and syringic) and five were hydroxycinnamic acids (chorogenic, caffeic, p-coumaric, ferulic and sinapic). The results showed that the content and composition of phenolic acids were significantly different between the types, cultivars and maturity of the fruits. The total phenolic acid of all as determined by RP-HPLC clearly decreased with ripening stage. A comparison of the phenolic acids levels of all fruits studied found that mango contained the highest total phenolic acids content (38.9–96.3 mg/g), followed by banana (5.8–11.2 mg/g) and papaya (1.0–2.5 mg/g). The amount of total phenolic acids in the green fruit of all fruits investigated was higher than that of the ripe fruit (Table 5). p-Hydroxybenzoic acid (p-HBA) was the most abundant phenolic acid in banana, with the concentration between 2.8 and 6.0 mg/g, whereas gallic acid (GA) was the most predominant phenolic acid in mango (9.1–62.1 mg/g), and GA and protocatechuic acid (PCCA) were the dominant phenolic acids in papaya but with only small quantities (0.1–0.7 and 0.2–0.5 mg/g, respectively). The other phenolic acids identified in the present study were minor constituents in all fruits investigated. These phenolic acids found in both green and ripe fruits from banana, mango and papaya were also identified in gac fruit (Kubola and Siriamornpun, 2011) and jujube fruit (Siriamornpun et al., 2015). Another study of various fruits collected in Mexico, including purple star apple, yellow cashew and red cashew, revealed that they contained high levels of gallic acid, ellagic acid, feruic acid and sinapic acid (Moo-Huchin et al., 2015).

3.3. Antioxidant capacities Changes in antioxidant activity of three fruits studied during ripening, as determined by DPPH and FRAP assays, are shown in Table 4. The overall results for antioxidant capacities (DPPH and FRAP assays) showed similar trends to TPC and vitamin C contents, which were found to decrease during ripening. Thus, the decrease in antioxidant capacity could be due to decreases in TPC and vitamin C content. The DPPH% scavenging activities of fruits studied were expressed as IC50 values, in which lower IC50 values indicate higher radical scavenging activity. Among all samples tested, the ripe fruit of Khai bananas showed the most potent DPPH% scavenging activity with an IC50 value of 1.47 mg/ml, whereas the green fruit of Holland papaya exhibited the lowest activity (IC50 = 5.37 mg/ml). The DPPH% scavenging activities of the green fruits of banana and mango among all cultivars studied showed higher IC50 values in the range 1.47–2.31 and 1.29–2.46 mg/ml, respectively, than the ripe fruit. These findings suggested that the green fruits of mango and banana with high amounts of phenolic compounds might play an important role in the inhibition of free radicals. For papaya, the antioxidant activity was greater for the ripe fruit than for the green fruit, possibly because the ripe fruit contains high β-carotene content.

3.5. Composition and content of bioactive flavonoids Flavonoids are one of the most important polyphenolic compounds with human health benefits due to their potent antioxidant and pharmacological effects (Miean and Mohamed, 2001; Khanam et al., 2012). In our study, six flavonoids, rutin, myricetin, luteolin, quercetine, apigenin and kaempferol, were identified and quantified in the green and ripe fruits from the three fruits studied using RP-HPLC (Table 6). We found that a similar trend in the phenolic acid results was observed in the flavonoids, in which the content and composition of 38

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Table 4 Antioxidant activity of green and ripe pulp extracts from three fruits studied. Fruits

DPPH radical scavengingIC50 (mg/ml)

FRAP value(mmol Fe(II)/g DW)

Green

Ripe

Green

Ripe

Banana Khai Hom mean

1.47 ± 0.15b,A 2.31 ± 1.27a,B 1.89

1.96 ± 0.11b,B 3.12 ± 1.53a,A 2.54

0.07 ± 0.01b,B 0.20 ± 0.01a,A 0.14

0.17 ± 0.02a,A 0.17 ± 0.02b,B 0.17

Mango Nam Dokmai Khiew Sawoey Kaew mean

2.46 ± 0.08a,B 2.15 ± 0.01b,B 1.29 ± 0.04c,B 1.97

2.80 ± 0.44a,A 2.56 ± 0.04b,A 1.97 ± 0.01c,A 2.44

0.86 ± 0.02b,A 0.65 ± 0.01c,A 1.21 ± 0.03a,A 0.91

0.07 ± 0.01c,B 0.15 ± 0.01b,B 0.79 ± 0.01a,B 0.34

Papaya Khak Dam Hawaii Holland mean

5.20 ± 0.09a,A 3.69 ± 0.12b,A 5.37 ± 0.16a,A 4.75

2.53 ± 0.09a,B 2.19 ± 0.04a,B 2.69 ± 0.01a,B 2.47

0.25 ± 0.02b,A 0.15 ± 0.01c,B 0.42 ± 0.03a,A 0.27

0.19 ± 0.01b,B 0.27 ± 0.01a,A 0.13 ± 0.01c,B 0.20

Results are expressed as mean ± SD (n = 3). Values with different letters in the same column (a–c) and in the same row (A–B) represent significant differences at p < 0.05.

flavonoids were significantly different depending on type, cultivar and ripeness of the fruit. The total flavonoids in green fruits of all fruits, except for mango, showed higher levels than that of ripe fruit. The differences in the amount of flavonoids may be due to the genetic variability and the ripening leading to variations in the biosynthesis of flavonoids in these fruits. When comparing types of fruits, mango had the highest total flavonoid content (103.9–1052.7 mg/g), followed by banana (21.9–427.4 mg/g) and papaya (32.0–92.7 mg/g). Rutin was the predominant flavonoid in banana and mango, while myricetin was the most abundant flavonoid in papaya. Luteolin, quercetine, apigenin and kaempferol were found in all fruits investigated, however only minor amounts were present. A previous study has reported myricetin was the most abundant flavonoid found in yellow cashew, which is a commonly consumed tropical fruit in Mexico (Moo-Huchin et al., 2015). In addition, our previous study demonstrated that the major flavonoids found in various cultivars of Thai jujube fruits were rutin, myricetin and apigenin (Siriamornpun et al., 2015). Based on our findings, we demonstrated that green fruits of all fruits studied could serve as potential sources of bioactive compounds, especially phenolics and flavonoids. Thus, this information may be useful for consumers who need to choose fruits that provide the highest specific bioactive compounds and health benefits. Moreover, we also think that the profile of bioactive compounds could be potential metabolite markers to determine ripening stages of three fruits studied.

p < 0.01, respectively). In our study, we think that these phenolic compounds were the most important contributors to the antioxidant capacity in the fruits studied. Numerous studies have reported a high positive correlation between phenolic compounds and antioxidant activity (Rufino et al., 2010; Schulz et al., 2015; Kaewseejan et al., 2015; Siriamornpun et al., 2015), whereas other authors have found no significant correlations (Amin et al., 2006; Sun and Ho, 2004). The differential presence or absence of significant correlations between phenolic compounds and antioxidant activity could be explained by the strong presence of a diversity of reducing agents in the fruits (Deepa et al., 2006) as well as genetic and environmental influences (Jagdish et al., 2007). Additionally, the correlation between the ripening stage with the bioactive compounds and antioxidant capacity was also studied (Table 7). The results of this study showed that some bioactive compounds were extremely positively correlated (p < 0.001) with the ripening stages (gallic acid, r = 0.865; vanillic acid, r = 0.965; chlorogenic acid, r = 0.992; sinapic acid, r = 0.991 and quercetin, r = 0.980). For vitamin C, β-carotene and caffeic acid, a very significant positive correlation was established with the ripening stages, in which the r values of 0.903, 0.882, 0.790 and 0.826, respectively. No significant correlations (p > 0.05) were observed between antioxidant capacities measured by the DPPH and FRAP methods with the ripening stages, as well as other variables. These findings suggest that the ripening stages of banana, mango and papaya increase (from green to ripe) the content of these bioactive compounds increases, while antioxidant capacity was not changed or varied by ripening. Similarly, Ding et al. (2001) demonstrated that the content of chlorogenic acid in loquat fruit increased 8.2-fold during ripening stage. Schulz et al. (2015) also reported that ripening increased the content of flavonoid quercetin in juçara fruit. In our study, we consider that the changes in bioactive compounds and antioxidant components of climacteric fruits studied could involve their biosynthesis pathways during ripening. Generally, the typical climacteric fruits are determined by climacteric peak in an increase the respiration rate and ethylene production during ripening. Thus, the increase in some individual phenolic compounds could be due to the increase respiratory processes that associated with ripening stage. Jacobo-Velázquez et al. (2011) suggested that respiratory processes can be generated free radicals at the end of the electron transport chain, where there is an increase in phenolic compounds biosynthesis in order to avoid oxidation and improve the mechanism of antioxidant defense in the plant tissue.

3.6. Correlation between various variables with fruit ripening stage Previously, many researchers have reported that there was a positive correlation between the content of bioactive compounds like phenolics or vitamin C and antioxidant activities in fruits (Moo-Huchin et al., 2014; Sampaio et al., 2015; Schulz et al., 2015). The correlation coefficient (r) between antioxidant capacity, crude fiber, TPC, vitamin C and β-carotene as well as individual phenolic acids and flavonoids in the three fruits studied were investigated in our study; however the data are not shown. Antioxidant activity measured by the DPPH assay showed a strong positive correlation with crude fiber content (r = 0.555; p < 0.01). There was not a significant correlation between antioxidant activity, measured by both methods (DPPH and FRAP), with TPC, vitamin C or β-carotene. However, a strong positive correlation was found between four individual phenolic acids (gallic, protocatechuic, p-coumaric and sinapic acids) and antioxidant capacity determined by the DPPH method, with r values ranging from 0.679 to 0.749 (p < 0.01). Among individual flavonoids, myricetin and luteolin demonstrated a significant positive correlation with antioxidant capacity measured by the FRAP (r = 0.483 and r = 0.759; 39

40

62.10 ± 2.01a 9.09 ± 0.01c 24.88 ± 4.81b 32.02

0.41 ± 0.01c 0.47 ± 0.02b 0.74 ± 0.01a 0.54

1.10 ± 0.06b 1.24 ± 0.01a 1.17

29.72 ± 3.06b 11.45 ± 0.23c 34.49 ± 5.78a 25.22

0.18 ± 0.01a 0.13 ± 0.04b 0.13 ± 0.01b 0.15

Mango Nam Dokmai Khiew Sawoey Kaew mean

Papaya Khak Dam Hawaii Holland mean

Ripe fruit Banana Khai Hom mean

Mango Nam Dokmai Khiew Sawoey Kaew mean

Papaya Khak Dam Hawaii Holland mean

0.24 ± 0.05b 0.20 ± 0.01b 0.43 ± 0.01a 0.29

1.50 ± 0.04b 1.06 ± 0.03c 2.54 ± 0.01a 1.70

0.59 ± 0.04a 0.45 ± 0.01b 0.52

0.43 ± 0.01b 0.50 ± 0.02a 0.39 ± 0.01c 0.44

9.82 ± 1.01a 7.42 ± 0.34b 1.74 ± 0.01c 6.33

0.70 ± 0.01a 0.51 ± 0.01b 0.61

ND ND 0.16 ± 0.01 0.16

1.51 ± 0.44 a 1.03 ± 0.15c 1.18 ± 0.05b 1.24

ND 6.03 ± 0.05 6.03

ND ND 0.25 ± 0.04 0.25

1.75 ± 0.13b 1.82 ± 0.18a 1.17 ± 0.12c 1.58

4.73 ± 0.13 ND 4.73

ND 0.11 ± 0.01 ND 0.11

2.80 ± 0.02b 3.76 ± 0.01a 0.47 ± 0.01c 2.34

0.37 ± 0.02a 0.12 ± 0.01b 0.25

0.11 ± 0.01 ND ND 0.11

1.83 ± 0.02a 1.56 ± 0.01b 0.30 ± 0.04 c 1.23

0.08 ± 0.02 0.10 ± 0.04 0.09

0.15 ± 0.04b 0.11 ± 0.01ab 0.20 ± 0.03a 0.15

1.04 ± 0.01c 2.76 ± 0.61b 5.59 ± 0.86a 3.13

0.36 ± 0.01a 0.26 ± 0.01b 0.31

ND ND 0.44 ± 0.01 0.44

1.17 ± 0.01a 0.91 ± 0.01b 0.94 ± 0.01b 1.01

0.28 ± 0.01 0.27 ± 0.01 0.27

SA

0.01 ± 0.00 ND ND 0.01

7.38 ± 2.01b 7.12 ± 0.12c 7.44 ± 2.31a 7.31

1.67 ± 0.01a 1.52 ± 0.01b 1.59

0.03 ± 0.03 ND ND 0.03

7.39 ± 0.21b 8.81 ± 0.01a 7.37 ± 0.02b 7.86

1.49 ± 0.01b 1.68 ± 0.02a 1.59

0.11 ± 0.01 0.11 ± 0.01 0.11 ± 0.01 0.11

1.00 ± 0.01b 1.04 ± 0.02b 1.76 ± 0.01a 1.27

0.31 ± 0.01a 0.23 ± 0.01b 0.27

ND ND 0.21 ± 0.01 0.21

1.03 ± 0.01b 1.71 ± 0.01a 1.01 ± 0.01b 1.25

0.24 ± 0.01b 0.47 ± 0.01a 0.36

CA

0.11 ± 0.02 0.11 ± 0.02 0.11 ± 0.01 0.11

0.90 ± 0.06 0.90 ± 0.13 0.90 ± 0.19 0.90

1.05 ± 0.86 ND 1.05

0.46 ± 0.02a 0.42 ± 0.01b ND 0.44

0.90 ± 0.02c 1.12 ± 0.03b 9.02 ± 0.24a 3.68

0.19 ± 0.02b 0.31 ± 0.07a 0.25

p-CoA

0.29 ± 0.01a 0.10 ± 0.03b 0.10 ± 0.02b 0.16

0.75 ± 0.62a 0.75 ± 0.12a 0.75 ± 0.44a 0.75

0.53 ± 0.02a 0.49 ± 0.04a 0.51

0.31 ± 0.01b 0.37 ± 0.04a 0.19 ± 0.01c 0.29

0.75 ± 0.01 0.75 ± 0.01 0.75 ± 0.24 0.75

0.74 ± 0.01b 1.22 ± 0.01a 0.98

FA

Results are expressed as mean ± SD (n = 3). Values with different letters in the same column represent significant differences at p < 0.05. GA, gallic acid; PCCA, protocatechuic acid; p-HBA, p-hydroxybenzoic acid; VA, vanillic acid; SA, syringic acid; CHA, chlorogenic acid; CA, caffeic acid; p-CoA, p-coumaric acid; FA, ferulic acid; SNA, sinapic acid. ND, not detected.

1.06 ± 0.01b 1.20 ± 0.01a 1.13

VA

CHA

p-HBA

GA

PCCA

Hydroxycinnamic acids (mg/g DW)

Hydroxybenzoic acids (mg/g DW)

Green fruit Banana Khai Hom mean

Fruits

Table 5 The content and composition of individual phenolic acids identified in green and ripe pulp extracts from three fruits.

0.11 ± 0.04 0.11 ± 0.04 0.11 ± 0.01 0.11

9.51 ± 0.98a 9.00 ± 1.02b 9.15 ± 2.52b 9.22

1.10 ± 0.98 ND 1.10

0.40 ± 0.04b 0.47 ± 0.01a 0.26 ± 0.01c 0.38

9.51 ± 0.24b 11.38 ± 0.05a 9.51 ± 0.65b 10.13

2.11 ± 0.04 ND 2.11

SNA

1.20 0.98 1.35 1.18

56.11 38.87 64.27 53.08

7.08 10.34 8.71

2.15 2.23 2.48 2.29

96.25 44.57 56.69 65.84

11.62 5.76 8.69

Total

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Table 6 Flavonoid content and composition of the green and the ripe fruits from three fruits cultivated in Thailand. Fruits

Flavonoid content (mg/g DW) Rutin

Myricetin

Luteolin

Quercetin

Apigenin

Kaempferol

Total

Green fruit Banana Khai Hom mean

139.50 ± 10.07b 162.39 ± 24.29a 150.95

4.40 ± 1.18b 5.64 ± 0.60a 5.02

2.26 ± 0.29a 0.10 ± 0.01b 1.18

1.86 ± 0.15b 5.19 ± 0.01a 3.53

7.81 ± 0.51b 11.22 ± 1.00a 9.52

16.32 ± 0.81a 15.66 ± 0.81b 15.99

172.15 200.20 186.18

Mango Nam Dokmai Khiew Sawoey Kaew mean

88.61 ± 2.26b 84.20 ± 0.05c 195.24 ± 8.32a 122.68

0.85 ± 0.01c 24.60 ± 0.27a 4.84 ± 0.21b 10.10

1.13 ± 0.07b 0.29 ± 0.07c 2.19 ± 0.31a 1.20

1.44 ± 0.02b 1.35 ± 0.02c 3.23 ± 0.05a 2.01

2.01 ± 0.02c 2.16 ± 0.01b 9.06 ± 0.20a 4.11

9.88 ± 0.32b 2.70 ± 0.02c 13.59 ± 1.67a 8.72

103.92 115.30 228.15 149.12

Papaya Khak Dam Hawaii Holland mean

4.24 ± 0.62b 6.39 ± 1.38a 3.74 ± 0.08c 4.79

40.39 ± 0.77c 76.96 ± 5.65a 43.15 ± 3.58b 53.50

0.57 ± 0.06a 0.28 ± 0.09b 0.29 ± 0.02b 0.38

1.83 ± 0.06c 2.04 ± 0.20a 1.85 ± 0.06b 1.91

4.71 ± 0.88a 3.00 ± 0.35b 2.81 ± 0.16c 3.51

3.49 ± 0.01b 4.06 ± 0.36a 3.83 ± 0.60b 3.79

55.23 92.73 55.67 67.88

Ripe fruit Banana Khai Hom mean

9.70 ± 0.21a 7.87 ± 1.15b 8.79

0.90 ± 0.10a 0.86 ± 1.16b 0.88

14.96 ± 0.39a 0.70 ± 0.07b 7.83

0.51 ± 0.07b 14.54 ± 0.09a 7.53

0.84 ± 0.02a 0.83 ± 0.07a 0.84

0.79 ± 0.03b 0.86 ± 0.04a 0.83

27.70 25.66 26.68

Mangos Nam Dokmai Khiew Sawoey Kaew mean

1037.58 ± 1.46a 231.79 ± 0.04c 712.43 ± 4.39b 660.60

1.35 ± 0.04b 21.08 ± 1.84a 0.96 ± 0.05c 7.80

0.60 ± 0.04a 0.18 ± 0.01b 0.10 ± 0.01c 0.29

1.46 ± 0.01b 1.03 ± 0.01c 1.69 ± 0.65a 1.39

1.92 ± 0.15b 1.62 ± 0.02c 2.07 ± 0.21a 1.87

9.74 ± 0.52a 2.30 ± 0.02b 10.14 ± 0.51a 7.39

1052.65 258.00 727.39 679.35

Papaya Khak Dam Hawaii Holland mean

8.19 ± 0.02a 4.32 ± 1.33b 5.76 ± 0.44b 6.09

11.30 ± 1.97b 17.10 ± 1.17a 15.56 ± 1.12a 14.65

0.59 ± 0.01c 0.79 ± 0.08a 0.64 ± 0.07b 0.67

2.38 ± 0.58b 2.51 ± 0.40a 2.47 ± 0.11b 2.45

3.74 ± 1.45c 9.56 ± 3.32a 7.89 ± 0.44b 7.06

5.81 ± 0.24c 17.99 ± 2.41a 10.77 ± 2.04b 11.52

32.01 52.27 43.09 42.46

Results are expressed as mean ± SD (n = 3). Values with different letters in the same column represent significant differences at p < 0.05. ND, not detected.

4. Conclusions

Table 7 Correlations between the bioactive compounds and antioxidant activities of three tropical fruit pulps with the ripening stages. Variable

Correlation coefficient (r)

The physicochemical properties and bioactive compounds of green and ripe fruits of Thai fruits (banana, mango and papaya) as well as antioxidant capacity are reported in this study. The variety and the maturity of fruit significantly influenced the physicochemical characteristics, bioactive compounds and antioxidant activity in all fruits studied. The ripening (from green to ripe) resulted in statistically increased TSS and the reductions of crude fiber, hardness, firmness and crispness. The highest contents of total phenolic and vitamin C were found in the green stage, as well as antioxidant capacity, while βcarotene was observed in the ripe stage. Based on RP-HPLC analysis, the amounts of total phenolic acids and total flavonoids in the fruits studied decreased dramatically during ripening. However, four individual phenolic acids (gallic, vanillic, chlorogenic and sinapic acids) and the individual flavonoid quercetin had an extremely positively correlation (p < 0.001) with the ripening stages, suggesting that ripening increases the levels of these phenolic compounds. In addition, gallic acid, protocatechuic acid, p-coumaric acid, myricetin and luteolin might be responsible for antioxidant capacity in the three fruits studied. This scientific evidence provides important information for fruit product consumers and practitioners to select an appropriate ripening stage of climacteric fruits studied that provides desirable quality and contains the highest amount of specific bioactive compounds as well as enhances health benefits.

p value

TPC Vitamin C β-Carotene

0.665 0.882 0.790

0.103 0.003 0.005

Individual phenolic acid Gallic acid Protocatechuic acid p-Hydroxybenzoic acid Vanillic acid Syringic acid Chlorogenic acid Caffeic acid p-Coumaric acid Ferulic acid Sinapic acid

0.865 0.529 0.198 0.965 0.701 0.992 0.826 0.466 0.378 0.991

< 0.001 0.116 0.583 < 0.001 0.024 < 0.001 0.003 0.174 0.282 < 0.000

Individual flavonoid Rutin Myricetin Luteolin Quercetin Apigenin Kaempferol

0.422 0.540 0.432 0.980 −0.771 0.120

0.225 0.107 0.211 < 0.000 0.832 0.582

Antioxidant capacity DPPH FRAP

0.589 0.590

0.433 0.163

Acknowledgments This research was financially supported by the Thailand Research 41

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total antioxidant capacity of selected leafy vegetables. J. Funct. Foods 4, 979–987. Kubola, J., Siriamornpun, S., 2011. Phytochemicals and antioxidant activity of different fruit fractions (peel, pulp, aril and seed) of Thai gac (Momordica cochinchinensis Spreng). Food Chem. 127, 1138–1145. Kubola, J., Meeso, N., Siriamornpun, S., 2013. Lycopene and beta carotene concentration in aril oil of gac (Momordica cochinchinensis Spreng) as influenced by aril-drying process and solvents extraction. Food Res. Int. 50, 664–669. Liu, H., Cao, J., Jiang, W., 2015. Changes in phenolics and antioxidant property of peach fruit during ripening and responses to 1-methylcyclopropene. Postharvest Biol. Technol. 108, 111–118. Medicinal Plants Information Center, 2017. Pharmacy Database of Thai Medicinal Plants. Mahidol University Available from. http://www.medplant.mahidol.ac.th/new/index. asp. Miean, H.K., Mohamed, S., 2001. Flavonoid (myricetin, quercetin, kaempferol, luteolin, and apigenin) content of edible tropical plants. J. Agric. Food Chem. 49, 3106–3112. Moo-Huchin, V.M., Moo-Huchin, M.I., Estrada-León, R.J., Cuevas-Glory, L., Estrada-Mota, I.A., Ortiz-Vázquez, E., Betancur-Ancona, D., Sauri-Duch, E., 2015. Antioxidant compounds, antioxidant activity and phenolic content in peel from three tropical fruits from Yucatan, Mexico. Food Chem. 166, 17–22. Nhung, D.T.T., Bung, P.N., Ha, N.T., Phong, T.K., 2010. Changes in lycopene and beta carotene contents in aril and oil of gac fruit during storage. Food Chem. 121, 326–331. Oreopoulou, V., Tzia, C., 2007. Utilization of plant by-products for the recovery of proteins, dietary fibers, antioxidants, and colorants. In: Oreopoulou, V., Russ, W. (Eds.), Utilization of By-Products and Treatment of Waste in the Food Industry. Springer Science Business Media Inc., New York, USA, pp. 209–232. Ornelas-Paz de, J., Yahia, E.M., Ramírez-Bustamante, N., Pérez-Martínez, J.D., EscalanteMinakata Mdel, P., Ibarra-Junquera, V., Acosta-Muñiz, C., Guerrero-Prieto, V., Ochoa-Reyes, E., 2013. Physical attributes and chemical composition of organic strawberry fruit (Fragaria x ananassa Duch, Cv. Albion) at six stages of ripening. Food Chem. 138, 372–381. Patthamakanokporn, O., Puwastien, P., Nitithamyong, A., Sirichakwal, P.P., 2008. Changes of antioxidant activity and total phenolic compounds during storage of selected fruits. J. Food Compos. Anal. 21, 241–248. Prasanna, V., Prabha, T.N., Tharanathan, R.N., 2007. Fruit ripening phenomena—an overview. Crit. Rev. Food Sci. Nutr. 47, 1–19. Ramful, D., Tarnus, E., Aruoma, O.I., Bourdan, E., Bahorun, T., 2011. Polyphenol composition, vitamin C content and antioxidant capacity of Mauritian citrus fruit pulps. Food Res. Int. 44, 2088–2099. Rangkadilok, N., Sitthimonchai, S., Worasuttayangkurn, L., Mahidol, C., Ruchirawat, M., Satayavivad, J., 2007. Evaluation of free radical scavenging and antityrosinase activities of standardized longan fruit extract. Food Chem. Toxicol. 45, 328–336. Rincón, A.M., Vásquez, A.M., Padilla, F.C., 2005. Composición química y compuestos bioactivos de las harinas de cáscaras de naranja (Citrus sinensis), mandarina (Citrus reticulata) y toronja (Citrus paradisi) cultivadas en Venezuela. Arch. Latinoam. Nutr. 55, 1–8. Rufino, M.S., Alves, R.E., Brito, E.S., Pérez-Jiménez, J., Saura-Calixto, F., Mancini-Filho, J., 2010. Bioactive compounds and antioxidant capacities of 18 non-traditional tropical fruits from Brazil. Food Chem. 121, 996–1002. Sampaio, C.R.P., Hamerski, F., Ribani, R.H., 2015. Antioxidant phytochemicals of Byrsonima ligustrifolia throughout fruit developmental stages. J. Funct. Foods 18, 400–410. Schulz, M., Borges, G.S.C., Gonzaga, L.V., Seraglio, S.K.T., Olivo, I.S., Azevedo, M.S., Nehring, P., Gois, J.S., Almeida, T.S., Vitali, L., Spudeit, D.A., Micke, G.A., Borges, D.L.G., Fett, R., 2015. Chemical composition, bioactive compounds and antioxidant capacity of juçara fruit (Euterpe edulis Martius) during ripening. Food Res. Int. 77, 125–131. Shahidi, F., Naczk, M., 2004. Phenolics in Food and Nutraceuticals. CRC Press, Boca Raton, FL. Siriamornpun, S., Weerapreeyakul, N., Barusrux, S., 2015. Bioactive compounds and health implications are better for green jujube fruit than for ripe fruit. J. Funct. Foods 12, 246–255. Sun, T., Ho, C.H., 2004. Antioxidant activities of buckwheat extracts. Food Chem. 90, 743–749. Tharanathan, R.N., Yashoda, H.M., Prabha, T.N., 2006. Mango (Mangifera indica L.), the king of fruits—an overview. Food Rev. Int. 22, 95–123. Tiwari, U., Cummins, E., 2013. Factors influencing levels of phytochemicals in selected fruit and vegetables during pre- and post-harvest food processing operations. Food Res. Int. 50, 497–506. Toivonen, P.M.A., Brummell, D.A., 2008. Biochemical bases of appearance and texture changes in fresh-cut fruit and vegetables. Postharvest Biol. Technol. 48, 1–14. Valente, A., Albuquerque, T.G., Sanches-Silva, A., Costa, H.S., 2011. Ascorbic acid content in exotic fruits: a contribution to produce quality data for food composition databases. Food Res. Int. 44, 2237–2242. Vasco, C., Ruales, J., Kamal-Eldin, A., 2008. Total phenolic compounds and antioxidant capacities of major fruits from Ecuador. Food Chem. 111, 816–823. Vuong, L.T., Dueker, S.R., Murphy, S.P., 2002. Plasma beta-carotene and retinol concentrations of children increase after a 30-d supplementation with the fruit Momordica cochinchinensis (gac). Am. J. Clin. Nutr. 75, 872–879. Wall, M.M., 2006. Ascorbic acid vitamin A, and mineral composition of banana (Musa sp.) and papaya (Carica papaya) cultivars grown in Hawaii. J. Food Compos. Anal. 19, 434–445. Yahia, E.M., Ornelas-Paz, J.D.J., Gonzalez-Aguilar, G.A., 2011. Nutritional and healthpromoting properties of tropical and subtropical fruits. In: Yahia, E.M. (Ed.), Postharvest Biology and Technology of Tropical and Sub-Tropical Fruits. Woodhead Publishing Co., Oxford, UK, pp. 21–78.

Fund (TRF), grant number RDG5120064. We also gratefully thank Dr. Jittawan Kubola for her technical assistance and Dr. Jolyon Dodgson for his help in improving the English. The authors have declared no conflicts of interest. References AOAC, 1998. 16th ed. Official Methods of Analysis of the Association of Official Analytical Chemists, vol. 2 Official methods of analysis of AOAC International, Washington, DC. Abushita, A.A., Hebshi, A.E., Daood, G.H., Biacs, A.P., 1997. Determination of an antioxidant vitamins in tomatoes. Food Chem. 60 (2), 207–212. Ajila, C.M., Bhat, S.G., Rao, U.J.S.R., 2007. Valuable components of raw and ripe peels from two Indian mango varieties. Food Chem. 102, 1006–1011. Akbari, V., Jamei, R., Heidari, R., Esfahlan, A.J., 2012. Antiradical activity of different parts of Walnut (Juglans regia L.) fruit as a function of genotype. Food Chem. 135, 2404–2410. Almeida, M.M.B., Sousa, P.H.M., Arriaga, A.M.C., Prado, G.M., Magalhaes, C.E.C., Maia, G.A., Lemos, T.L.G., 2011. Bioactive compounds and antioxidant activity of fresh exotic fruits northeastern Brazil. Food Res. Int. 44, 2155–2159. Amin, I., Norazaidah, Y., Emmy Hainida, K.I., 2006. Antioxidant capacity and phenolic content of spinach species (Amaranthus sp.). Food Chem. 94, 47–52. Aoki, H., Kieu, M.T.N., Kuze, N., Tomisaka, K., Chuyen, V.N., 2002. Corotenoid pigments in gac fruit (Momordica cochinchinenensis Spreng). Biosci. Biotechnol. Biochem. 66 (11), 2479–2482. Bakar, M.F.A., Mohamed, M., Rahmat, A., Fry, J., 2009. Phytochemicals and antioxidant activity of different parts of bambangan (Mangifera pajang) and tarap (Artocarpus odoratissimus). Food Chem. 113, 479–483. Bashir, H.A., Abu-Goukh, A.A., 2003. Compositional changes during guava fruit ripening. Food Chem. 80, 557–563. Benchikh, Y., Louaileche, H., George, B., Merlin, A., 2014. Changes in bioactive phytochemical content and in vitro antioxidant activity of carob (Ceratonia siliqua L.) as influenced by fruit ripening. Ind. Crops Prod. 60, 298–303. Benzie, I.F., Strain, J.J., 1996. The ferric reducing ability of plasma (FRAP) as a measure of ‘antioxidant power’: the FRAP assay. Anal. Biochem. 239, 70–76. Brand-Williams, W., Cuvelier, M.E., Berset, C., 1995. Use of free radical method to evaluate antioxidant activity. LWT Food Sci. Technol. 28 (1), 25–30. Cardoso, L.M., Martino, H.S.D., Moreita, A.V.B., Ribeiro, S.M.R., Santana, H.M.P., 2011. Cagaita (eugenia dysenterica DC.) of the Cerrado of Minas Gerais, Brazil physical and chemical characterization, carotenoids and vitamins. Food Res. Int. 44, 2151–2154. Charoensiri, R., Kongkachuichai, R., Suknicom, S., Sungpuag, P., 2009. Beta-carotene, lycopene, and alpha-tocopherol contents of selected Thai fruits. Food Chem. 113, 202–207. de Carvalho-Silva, L.B., Dionísio, A.P., da Silva Pereira, A.C., Wurlitzer, N.J., de Brito, E.S., Bataglion, G.A., Brasil, I.M., Eberlin, M.N., Liu, R.H., 2014. Antiproliferative, antimutagenic and antioxidant activities of a Brazilian tropical fruit juice. LWT Food Sci. Technol. 59, 1319–1324. De Souza, V.R., Pereira, P.A.P., Queiroz, F., Borges, S.V., Carneiro, J.D.S., 2012. Determination of bioactive compounds, antioxidant activity and chemical composition of Cerrado Brazilian fruits. Food Chem. 134, 381–386. Deepa, N., Kaur, C., Singh, B., Kapoor, H.C., 2006. Antioxidant capacity in some red sweet pepper cultivars. J. Food Compos. Anal. 19, 572–578. Deng, G.F., Lin, X., Xu, X.R., Gao, L.L., Xie, J.F., Li, H.B., 2013. Antioxidant capacities and total phenolic contents of 56 vegetables. J. Funct. Foods 5, 260–266. Ding, C.K., Chachin, K., Ueda, Y., Imahori, Y., Wang, C.Y., 2001. Metabolism of phenolic compounds during loquat fruit development. J. Agric. Food Chem. 49, 2883–2888. Eskin, N.A.M., Hoehn, E., Shahidi, F., 2013. Fruits and vegetables. In: Eskin, N.A.M., Shahidi, F. (Eds.), Biochemistry of Foods. Academic Press, San Diego, pp. 49–126. Gayosso-Garcia, S.L., Yahia, E.M., Martinez, M.A., Gonzalez-Aguilar, G., 2010. Effect of maturity stage of papaya Maradol on physiological and biochemical parameters. Am. J. Agric. Biol. Sci. 5 (2), 199–208. Gruz, J., Ayaz, F.A., Torun, H., Strnad, M., 2011. Phenolic acid content and radical scavenging activity of extracts from medlar (Mespilus germanica L.) fruit at different stages of ripening. Food Chem. 124, 271–277. Hung, H., Joshipura, K.J., Jiang, R., Hu, F.B., Hunter, D., Smith-Warner, S.A., Colditz, G.A., Rosner, B., Spiegelman, D., Willett, W.C., 2004. Fruit and vegetable intake and risk of major chronic disease. J. Natl. Cancer Inst. 96 (21), 1577–1584. Ibarra-Garza, I.P., Ramos-Parra, P.A., Hernández-Brenes, C., Jacobo-Velázquez, D.A., 2015. Effects of postharvest ripening on the nutraceutical and physicochemical properties of mango (Mangifera indica L. cv Keitt). Postharvest Biol. Technol. 103, 45–54. Isabelle, M., Lee, L.B., Lim, T.M., Koh, P.W., Huang, D., Ong, N.C., 2010. Antioxidant activity and profiles of common fruits in Singapore. Food Chem. 123, 77–84. Jacobo-Velázquez, D.A., Martínez-Hernández, G.B., Del, C., Rodríguez, S., Cao, C.M., Cisneros-Zevallos, L., 2011. Plants as biofactories: physiological role of reactive oxygen species on the accumulation of phenolic antioxidants in carrot tissue under wounding and hyperoxia stress. J. Agric. Food Chem. 59, 6583–6593. Jagdish, S., Upadhyay, A.K., Kundan, P., Anant, B., Mathura, R., 2007. Variability of carotenes, vitamin C, E and phenolics in Brassica vegetables. J. Food Compos. Anal. 20, 106–112. Kaewseejan, N., Sutthikhum, V., Siriamornpun, S., 2015. Potential of Gynura procumbens leaves as source of flavonoid-enriched fractions with enhanced antioxidant capacity. J. Funct. Foods 12, 120–128. Khanam, U.K.S., Oba, S., Yanase, E., Murakami, Y., 2012. Phenolic acids, flavonoids and

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